The objectives of this project are to define the biochemical changes that platelets undergo during storage at predetermined temperatures and periods of time. The effect of storage on the vital functions and interrelationships of the microstructural elements composing the cytoskeleton of platelets, known only partially, is the subject of these studies. We propose to investigate the stability of the platelet cytoplasm, including cytopoasmic proteins, in order to devise conditions for platelets to preserve intact their mitochondrial population, the proteins and enzymes composing their cytoplasm, and the integrity of their membranes. We believe that the identification of these changes are the best indicators for assuring conditions that will permit optimal preservation of platelet functions and their survival in vivo for patients in need of these blood elements. The goals set for the current year are to determine if platelets stored with specific preservatives, such as glycerine, and stored at temperatures below their freezing point can be prevented from deteriorating and releasing their metabolites, which then become the active agents for the surrounding platelets to undergo processes of aggregation and release.